First, let me say that i support the use of marijuana to control pain the terminally ill patients. The use and dosing rationale is easily understood: smoke until you feel no more pain. However where I differ is the use of marijuana for glaucoma.
Glaucoma is a life long condition that if untreated results in permanent blindness through gradual loss of peripheral vision. The disease progresses until no vision is left. If correctly diagnosed, usually by noting a rise in the pressure inside the eye, glaucoma can most often be treated with medication and sometimes surgery. Glaucoma exists for the remainder of that person’s life, requiring treatment and regular checkups to ensure that the treatment is still working.
Most drugs that we use in medicine are naturally derived, or at least the parent drug was naturally derived. The standardization of dosing of drugs arose with better understanding of various disease processes. The desire to standard medications in turn led to the growth of the pharmaceutical industry.
Glaucoma, as with other diseases, requires proper dosing for around the clock control. The control is determined from experiments, mostly sponsored by the pharmaceutical companies, monitoring eye pressure and ocular damage in large groups of patients for many months. From these experiments are derived the standardized concentrations and frequencies of administration of the drug under study. These experiments are corroborated by independent researchers and published in peer-reviewed journals. This peer-review system ensures integrity of the data. As a physician, I can thus be assured that the various glaucoma drugs work as described. I can with confidence use them to control glaucoma. I can with certainty describe their use to a patient.
However, with marijuana there is no standard. What would the dosing be? How much should be smoked and how often? What quality of marijuana should be used and how would one quantitate quality with quantity?
The typical answer by supporters of medicinal marijuana is simply have the patient use more or less drug until the pressure is controlled. Unfortunately the problem is not that simple. Who will measure the pressures, and how often do the pressures need monitoring? Also, are the measured pressures sufficiently low to prevent additional blindness? Such an approach requires too much time (during which the patient could go blind), and forces the physician and patient to attempt to replicate experiments on an individual basis that are normally done by the pharmaceutical industry on large populations. Such experimentation in neither safe nor practical, and potentially exposes the practitioner to litigation that could arise from a patient who went blind from inadequate control with marijuana.
Thus my belief is that the medical use of marijuana for control of glaucoma is not wise and I do not recommend such treatment for my patients.
